Yoshihito Okubo

Effective diffusivities of lighter hydrocarbons in Cu- and Co-MFI-type zeolite catalysts

Abstract Intracrystalline and effective diffusivities of ethane, propane, ethylene and propylene were measured for several kinds of MFI-type zeolite, such as silicalite-1, H-MFI, Cu- and Co-MFI-type zeolites at temperatures ranging from 323 to 823 K . The intracrystalline diffusivity represents the mobility of molecules within zeolite crystals, and was found to be reduced to 1/100 for paraffins and 1/1000 for olefins by the existence of active sites (proton, Cu and Co ions), as compared with silicalite-1. The effective diffusivity was evaluated by multiplying the intracrystalline diffusivity by a partition factor. Although the intracrystalline diffusivity of olefins was about 1/10 to 1/100 of that of paraffins, the effective diffusivity of olefins was almost equal to that of paraffins. The calculated effective diffusivity of ethylene within Cu-MFI was in good agreement with those evaluated by the kinetic analysis of the catalytic decomposition of NO with ethylene over Cu-MFI catalyst.

Oxidative Dimerization of Phenol Based on Micromixing in Single-And Two-Phase Systems

It is an important technique to obtain target products with higher yields by controlling the reaction and mass transfer. In this work, we focused on molecular weight control in the oxidative polymerization of phenol. We attempted selective production of phenol dimers through the formation of microdroplets in both single- and two-phase systems. In a single-phase system, selectivity of dimers to polymers can be improved by rapidly mixing ingredients using a micromixer. Further, we clarified the conditions to utilize such microspace effects by comparing the initial reaction time constant with the mixing time constant by order-of-magnitude estimation. In a two-phase system, it was clarified that controlling of mass transfer by formation of microdroplets using a micromixer was effective in the control of consecutive elementary reactions though the dimer selectivity hardly changes and the effect of micromixing was limited.